Means for supplying liquid fuel to spill type burners in prime movers



March 30, 1954 O. MEANS FOR SUPPLYING LIQUID FUEL TO SPILL N. LAWRENCE2,673,604

TYPE BURNERS IN PRIME MOVERS Filed May 11, 1951 Patented Mar. 30, 1954MEANS FOR SUPPLYING LIQUID FUEL. TO

. SI fILL TYPE BURNERS IN PRIME MOVERS Owen Napier Lawrence, Dorridge,England, as-

signor to Joseph Lucas Limited, Birmingham,

England Application May 11, 1951, Serial No. 225,696

I Claims priority, application Great Britain May 22, 1950 This inventionhas for its object to provide means for supplying liquid fuel at avariable rate to the burner of such a prime mover as a jet-engine or gasturbine, the burner comprising one or more nozzles of the swirl-type,and having associated therewith a spill pipe for turning excess fuelsupplied for maintaining an effective swirl condition.

The invention comprises the combination of a centrifugal fuel-supplypump, and adjustable means for connecting the discharge end of theburner spill pipe to a variable position between the pump inlet andoutlet.

The invention also comprises means for automatically actuating theadjustable means.

The accompanying drawing represents diagrammatically one embodiment ofthe invention.

Referring to the diagram, a centrifugal pump of any convenient form isemployed for supplying the liquid fuel to the burner or burners, thepump housing a being provided with a connection for a supply pipe bleading to the burner 0. One side of the pump impeller d is open, andadjacent to this side there is formed in the housing a radial chamber ewhich at one side is exposed to the impeller. In this chamber isarranged a slidable plunger 1 having therein a radial port g facing theopen side of the impeller, and the port communicates with one end of alongitudinal passage h, in the plunger, the other end being adapted forthe connection thereto of a flexible end of the spill pipe 2' connectedto the burner.

When the pump is in action a pressure gradient exists in the impeller,and by moving the plunger to bringthe said port g to an appropriateposition on the gradient, any desired pressure difference can be set upin the spill pipe for varying the rate of return fiow of excess fuelfrom the burner to the pump.

To enable the return flow of excess fuel to be maintained substantiallyconstant, or to be otherwise controlled, the plunger may conveniently beactuated by a liquid operated servo-mechanism. Such a mechanismcomprises a piston is attached to the plunger, the piston being slidablein a cylinder m the opposite ends of which are in communication by wayof a restricted orifice n. One end of the cylinder is adapted forconnection to the pump outlet by a pipe 0, or the fuel supply pipeleading to the burner. The other end is provided with an outlet which isconnected by a pipe 11 to the seating q of a normally-closed valve 1'.The valve is operable by a lever s which in turn is operable by a stem textending from a 5 Claims. (01. 15s'-'-3s.4)

diaphragm it which divides into two compartments 1), w from whichpassages lead to two points in the pump housing which are open atdifferent radial positions to the open side of the impeller. The twosides of the diaphragm are thus subject to a liquid pressure differencewhich depends on the rate of rotation of the impeller. When thisdiiference exceeds a predetermined amount, the diaphragm causes thevalve to be opened. The servo-mechanism thereupon moves the plungertowards the axis of the impeller so increasing the pressure differencein the spill pipe and causing an increase in the return flow, withcorresponding reduction of the supply of fuel to the burner until theprevious condition is restored.

The diaphragm above mentioned is loaded by a spring a: which isadjustable by a manually operable lever y for enabling the output of thepump to be varied to suit different working conditions.

By this invention the automatic control of a fuel supply system to aburner having a nozzle or nozzles of the swirl-type can be effected in avery simple manner.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel supply system comprising in combination a centrifugalpump having a fuel inlet and fuel discharge outlet, a burnercommunicating with said outlet and having at least one fuel dischargenozzle of the swirl-type, a spill pipe communicating at one end withsaid burner and at the opposite end with said pump at a position betweensaid inlet and outlet so that excess liquid fuel supplied by said pumpto said burner for maintaining an effective swirl condition at saidnozzle returns to said pump through said spill pipe at a rate dependenton the fuel pressure in the part of said pump communieating with saidspill pipe, and adjustably displaceable means for varying the positionat which said pump communicates with said spill pipe, and therebyvarying the rate of return fuel fiow through said spill pipe.

.2, A liquid fuel supply system according to claim 1 and havingautomatic means for moving said displaceable means.

3. A liquid fuel supply system comprising in combination a centrifugalpump formed by a rotary impeller in a housing having a fuel inlet and afuel discharge outlet, a burner communicating with said outlet andhavingbat least one fuel discharge nozzle of the swirl type, a spillpipe communicating at one end with said burner, a chamber in saidhousing at one side of said impeller, a plunger slidably adjustable insaid chamber and having there-in a passage through the medium of whichthe opposite end-of said spill pipe communicates with the interior ofsaid housing at a position between said inlet and outlet so that excessliquid fuel supplied by said pump to said burner for maintaining aneffective swirl condition at said nozzle returns to said pump throughsaid spill pipe at a rate dependent on the fuel pressure in the part ofsaid pump communicating with said spill pipe, and means foractuatingsaid plunger for varying the position at which said spill pipecommunicates through said passage with said housing, and thereby varyingthe rate of return flow of fuel through said spill pipe.

4. A liquid fuel supply system according to claim 3, in which the meansfor actuating the plunger comprises a liquid-operated servomechanismhaving controlling means responsive to a liquid pressure difference inthe impeller of said pump.

5. A liquid fuel supply system according to claim 4, in which the meansfor controlling the servo-mechanism comprises in combination a valve,afl-diaphrzig'm for actuating said valve in response to a liquidpressure difierence in the pump, a loading spring acting on saiddiaphragm, and manually operable means for adjusting said spring.

OWEN NAPIER LAWRENCE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,407,139 Clothier Sept. 3, 1946 2,523,214 'Ifleld Sept. 19,1950 2,616,507 Greenland Nov. 4, 1952 2,619,163 Wynne et al. Nov. 25,1952 I FOREIGN PATENTS Number Country Date 618,145 Great Britain Feb.17, 1949

